It makes a huge difference whether you can pre-populate a new network with a list of your friends, as it makes your friends' discovery possible. Imagine, which

It makes a huge difference whether you can pre-populate a new network with a list of your friends, as it makes your friends' discovery possible. Imagine, which Google+ launched, how things might have gone if 5% of Facebook users could have moved their own social graphs to G+ with two clicks of a mouse. If everyone had 100 friends, and those friends were uniformly distributed (all stark simplifying assumptions), then a huge fraction of the global social graph could have been moved to the new network by a small fraction of the users.